Salt Lake City Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Salt Lake City (Salt Lake City, UT area) was March 2, 2024, when the daily AQI reached 230 (Very Unhealthy), set by coarse dust (PM10). Across 2,557 monitored days in 2019–2025, 10 of the 10 worst days were Unhealthy (AQI 151+) or worse; 5 of the 10 were driven by ground-level ozone and 3 by fine particulate matter (PM2.5), and 5 of them fell in 2021. The cleanest day was October 12, 2021 at AQI 27 (Good); the 10 best days span 5 different years.
Extra Protection for Salt Lake City Homes
Air quality in Salt Lake City is moderate (AQI 52), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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When were Salt Lake City's worst and best air quality days?
Worst: March 2, 2024, AQI 230 (Very Unhealthy, PM10). Best: October 12, 2021, AQI 27 (Good). Based on 2,557 EPA-monitored days in the Salt Lake City, UT area, 2019–2025.
- ✓10 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 156 (Unhealthy).
- ✓Ground-level ozone drove 5 of the 10 worst days.
- ✓2021 accounts for 5 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Salt Lake City?▾
March 2, 2024: the Salt Lake City, UT area's daily AQI hit 230 (Very Unhealthy), driven by coarse dust (PM10). That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Salt Lake City?▾
October 12, 2021, with a daily AQI of 27 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Salt Lake City's worst air quality day in 2025?▾
May 12, 2025, AQI 175 (Unhealthy), set by coarse dust (PM10).
Which pollutant causes Salt Lake City's worst air days?▾
Ground-level ozone set the AQI on 5 of the 10 worst days; fine particulate matter (PM2.5) on 3. The tables above list the defining pollutant for every day.
Salt Lake City's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Salt Lake City, UT area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2024 page) | 230 | Very Unhealthy | PM10 — coarse dust (PM10) |
| 2 | (2020 page) | 214 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2021 page) | 177 | Unhealthy | O3 — ground-level ozone, in peak ozone season |
| 4 | (2025 page) | 175 | Unhealthy | PM10 — coarse dust (PM10) |
| 5 | (2021 page) | 164 | Unhealthy | O3 — ground-level ozone, in peak ozone season |
| 6 | (2020 page) | 162 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 7 | (2021 page) | 159 | Unhealthy | O3 — ground-level ozone, in peak ozone season |
| 8 | (2021 page) | 157 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 9 | (2024 page) | 156 | Unhealthy | O3 — ground-level ozone, in peak ozone season |
| 10 | (2021 page) | 156 | Unhealthy | O3 — ground-level ozone, in peak ozone season |
Worst day of each year in Salt Lake City
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 136 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2020 | 214 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2021 | 177 | Unhealthy | O3 — ground-level ozone, in peak ozone season | |
| 2022 | 147 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2023 | 154 | Unhealthy | O3 — ground-level ozone, in peak ozone season | |
| 2024 | 230 | Very Unhealthy | PM10 — coarse dust (PM10) | |
| 2025 | 175 | Unhealthy | PM10 — coarse dust (PM10) |
Salt Lake City's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Salt Lake City, UT area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2021 page) | 27 | Good | O3 — ground-level ozone |
| 2 | (2019 page) | 27 | Good | NO2 — nitrogen dioxide |
| 3 | (2023 page) | 28 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2023 page) | 29 | Good | O3 — ground-level ozone |
| 5 | (2019 page) | 29 | Good | O3 — ground-level ozone |
| 6 | (2025 page) | 31 | Good | O3 — ground-level ozone |
| 7 | (2025 page) | 31 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2024 page) | 31 | Good | O3 — ground-level ozone |
| 9 | (2024 page) | 31 | Good | O3 — ground-level ozone |
| 10 | (2023 page) | 31 | Good | O3 — ground-level ozone |
Right now in Salt Lake City
The latest EPA AirNow observation puts Salt Lake City's AQI at 52 (PM2.5). The days above are historical records, not today's reading.
View current Salt Lake City air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Salt Lake City, UT), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.